Block copolymers and process for their preparation

ABSTRACT

A block copolymer having structural formula A-B or A-B-A, wherein A is a crystallizable isotactic polypropylene block segment and B is an amorphous olefin elastomeric block segment; the novel crystallizable block copolymer may be used as it is as a molding material, or as a compatibilizer, a surfactant, a mechanical property improvement agent and the like for other polyemers.

This application is the U.S. national phase of International ApplicationPCT/EP02/00278, filed Jan. 10, 2002, and published Aug. 29, 2002 in theEnglish language.

FIELD OF THE INVENTION

The present invention relates to a block copolymer comprising one ormore crystallizable isotactic polypropylene block segments and anamorphous olefinic elastomeric block segment. The present invention alsorelates to a process for the production thereof and the use thereof.

PRIOR ART DISCLOSURE

In the production of polymer blends or polymer alloys containing acrystalline phase and an amorphous polymer phase as the secondcomponent, it is usually necessary to compatibilize the elastomerfraction to obtain surface activation, modification and improvement ofmechanical properties in a higher order structure, by using varioustechniques, such as dispersion or emulsification in a polymer matrix.

A block copolymer may be used as a compatibilizer, to improve thecompatibility between a polymer matrix and an elastomer component whichare immiscible with each other. Common compatibilizers used in the artare block copolymers, graft copolymers containing a matrix polymerchain, or block copolymers having a reactive functional group (L. G.Lundsted, I. R. Schmolka, “Block and Graft Copolymerisation”, R. J.Ceresa Wiley, London vol. 2, page. 113 (1976); I. R. Schomolka, J. Am.Oil Chem. Soc. 54:110 (1977); and I. Piirma, Macromol. Chem., Macromol.Symp. 35/36:467 (1990)). In the block copolymers mentioned above, everysegment of the block chain is an amorphous polymer.

When in a polymer blend or a polymer alloy both the matrix component andthe second elastomeric component are amorphous polymers, it is possibleto disperse the second component into the polymer matrix by using, as acompatibilizer, a block copolymer consisting of these two components.

When one of the polymer blend components is crystallizable, as aproperty improvement agent is commonly used a block copolymer consistingof the two components in amorphous state; for instance,poly(styrene-ethylene-butylene-styrene) block copolymer (SEBS), obtainedby hydrogenation of a styrene-butadiene block copolymer, is generallyused as a property improvement agent for crystallizable polypropylene(JP-A-1989-149845, corresponding to GB 2213156).

However, even in the case of a block copolymer miscible with both thematrix and the second component, the block copolymer itself forms anintramolecular cohesive micelle, that may act as a low molecular weightsurfactant, depending on the composition of the block copolymer, thusforming a micro phase separation structure. The negative effect is thatthe block copolymer has a tendency to form an intramolecular cohesivemicelle (and induces micro phase separation) in a concentration higherthan the critical micellar concentration under which the secondcomponent can disperse in the matrix. In this way, the high micellarconcentration does not contribute to the compatibilization of the secondcomponent.

Furthermore, the use of these block copolymers impairs the phasestability of the polymer blend, due to the phase transition behavior ofthe micro phase separation, which depends upon temperature andcomposition.

Therefore, while at the time of manufacturing it is easy to obtainpolymer blends wherein the matrix component and the second component arecompatibilized, it is subsequently observed the decompatibilization anddecomposition of the second component, when the blends are modified (forinstance by increasing the matrix to dilute the second component) orundergo thermal treatments (during the melt mixing and/or stagnation, inthe process from the first to the higher order finishing processes) orare further reheated during recycling operations. These drawbacks makeit difficult to reach the essential target, such as the stabilization ofhigher order structure as a micro dispersed structure, and theimprovement of mechanical properties. Therefore, it is felt the need todevelop a block copolymer, having an optimized block segment structureand length, which is able to promote the formation of micelles in dilutesystem, and has dispersion and emulsifying ability; moreover, it is feltthe need of a block copolymer able to give dilution stability andallowing the reduction of the quantity of compatibilizer to be used in apolymer blend system.

The crystallization of polymers is of great technological importance dueto the mechanical properties imparted, which ultimately result from thechange in macromolecular conformation.

Since crystallization leads to extended conformation or to kineticallycontrolled chain folding by thermal hysteresis and outer field, thedifference of average length of folds strongly affects the mechanicalproperties of polymers.

In order to improve the impact strength of a crystalline polymer matrix,it is known in the art that a rubbery or glassy composition can be addedas a second component; nevertheless, due to the conformational change ofthe crystalline matrix that occurs during the mixing process, themechanical properties of the obtained compositions are in general lesssatisfactory than the those expected by summing up the properties of thetwo separate components (Leszak. A. Utracki, “Polymer Alloys and Blends:Thermodynamics and Rheology”, Hanser, Oxford Press, New York, 1989).

Besides the use of block copolymers consisting solely of amorphous blocksegments, in the state of the art it was proposed the possibility ofcontrolling higher order structure, including conformation, by using ablock copolymer containing a crystallizable chain (I. W. Hamley,“Crystallization in Block Copolymers” Advances in Polymer Science, vol.148, pag. 113 (1999)). More specifically, it was proposed to use a blockcopolymer and a graft copolymer containing one or more kinds ofcrystallizable polymers, in the range of one to all block segments, inorder to obtain a macro-stable structure containing crystallizablephases and to control the intramolecular cohesive micelle (micro phaseseparation), by defining the components and structure of each ofcrystallizable and amorphous block segments of the copolymers.

In the above document, the crystallizable block segment of the blockcopolymers consisted of poly(ethylene), poly(oxyethylene), poly(ethyleneglycol), poly(tetrahydrofuran) or poly(epsilon-caprolacton).

However, when trying to improve the resin properties by includingcrystallizable polymers such as isotactic polypropylene or polyamideknown as engineering plastics, of which there is a great demand on themarket, it must be remembered that different monomers for crystallizablepolymers and amorphous polymers behave in a very different way, asregards their polymerization activity, polymerization mechanism andpolymerization catalysts; block copolymers and graft-copolymer-blockcopolymers containing at least one kind of such crystallizable polymershas not been synthesized yet and isolated with a clear evidence of itslinear structure (JP-A-1996-092338, corresponding to EP 703 253, andJP-A-1997-241334, corresponding to U.S. Pat. No. 6,211,300).

Several authors have shown the formation of partially atactic, partiallyisotactic polypropylenes which have elastomeric properties. Propylenehomopolymers, containing different levels of isotacticity in differentportions of the molecule, are described by R. Waymouth in U.S. Pat. No.5,594,080; nevertheless, the block polymer chain structure is not welldefined and controllable.

U.S. Pat. No. 6,159,567 discloses a propylene block copolymer comprising(A) 60–90% wt. of a first block of a propylene polymer and (B) 40–10% wtof a second block of an ethylenepropylene copolymer, containing 1–10% wtof ethylene. In U.S. Pat. No. 5,391,629, it is described a process forthe production of block copolymers of ethylene and an alpha-olefin, byusing an ionic catalyst system including a metallocene catalyst. Theblock copolymers produced in these documents do not contain a totallyamorphous segment.

Under the above circumstances, the problem addressed by the presentinvention is to provide a new crystallizable block copolymer that allowsthe obtainment of polymer blends or polymer alloys having improvedbalance of properties with respect to the existing materials; said blockcopolymer must possess high mechanical strength, excellent modulus,thermal resistance and impact strength, and must show a wide thermalwindow for processing, so that the occurrence of non-decompatilizationand other molding defects, such as flow marks, due to low moldability isavoided or decreased when said block copolymer is used as acompatibilizer for crystallizable polymers, as a surfactant, as amodifier and mechanical-property-improvement agent, or when used as thesole component. By using said block copolymer, the variation of thecomposition and the decompatibilization during heating would not beencountered, the higher order of structure such as dispersion abilitywould be stably formed and the conformation variation which decreasesthe character of the crystalline would not be substantially encountered.

SUMMARY OF THE INVENTION

The present invention concerns a block copolymer having formula:A-B   (I)orA-B-A   (II)wherein A is a crystallizable isotactic polypropylene block segment(Block A segment), and B is an amorphous olefinic elastomeric blocksegment (Block B segment).

DETAILED DESCRIPTION OF THE INVENTION

In the following is reported the detailed description of the presentinvention.

The block A segment of the block copolymer of the present invention is acrystallizable isotactic polypropylene block segment, and preferablypropylene homopolymer or a copolymer of propylene with one or morealpha-olefins, having a number of carbon atoms up to about 20, such asethylene and butene-1.

The content of alpha-olefin in the block A segment of these copolymersis preferably ≦10% mol, in order not to reduce the crystallinity of saidcopolymers.

More preferably, the isotactic polypropylene block segment is highlystereoregular.

The isotactic pentad ratio (IP) of the isotactic polypropylene blocksegment mentioned above, measured by ¹³C-NMR spectroscopy, is preferably≧85.0%, and more preferably ≧95.0%.

The greater is the IP ratio, the higher is crystallinity and the betteris the effect of the present invention. The above mentioned IP ratio ismeasured by the method described in Macromolecules, Vol. 6, page 925(1973).

The IP ratio represents the percentage of the isotactic pentads, basedon the total number of chiral centers, in a polypropylene chain,measured by ¹³C-NMR spectroscopy. In the block copolymers of the presentinvention, the IP ratio is measured on the intermediate polypropyleneblock segment A, used to prepare the new block copolymer. The IP valueswere measured using the mmmm stereochemical shift strength ratio of theall stereochemical shifts within the methyl-carbon region of ¹³C-NMRspectroscopy, by assigning the stereochemical shifts according to therevised edition of the above-mentioned literature, as shown in theMacromolecules, Vol. 8, page 687 (1975).

The molecular weight of the Block A segment of the present inventionmust be sufficient to guarantee that the polymer chain length impart tothe polymer a crystallizable nature.

More specifically, the degree of polymerization is preferably ≧5, morepreferably ≧10. A sufficient crystallization ability is provided if thechain length is long enough to maintain a certain lamella thickness ofthe polypropylene crystals. There is no upper limit of the molecularweight, as long as the appropriate melt fluidity is maintained.Preferably the degree of polymerization ranges from 5 to 200,000, andmore preferably from 10 to 100,000.

The term “crystallizable”, as used herein for the Block A segment,characterizes those crystalline polymer segments which possess highdegrees of inter- and intramolecular order, and which have a meltingpoint preferably higher than 100° C., more preferably higher than 115°C., and preferably have a heat of fusion ΔH higher than 75 J/g, asdetermined by DSC analysis.

A narrow molecular weight distribution is preferable for the blockcopolymer of the present invention, since it must be able to control thecrystallizable structure of the isotactic polypropylene block segment,this ability being one of the characteristics of the present invention.

The polymer crystallization is of high technical importance, since themechanical properties are highly affected thereby, and it ultimatelyresults from the macromolecular conformation and from the kineticallycontrolled chain folding.

On the other hand, crystallization in the novel block copolymer of thepresent invention leads to an equilibrium number of holds, as can becontrolled by the size of the second, amorphous block B.

In order to obtain homogeneously the equilibrium number of holds, anarrow molecular weight distribution of the crystallizable block Asegment is preferable. Mw/Mn is preferably ≧2.5, and more preferably≧2.0.

These narrow molecular weight distribution values may be obtained withmethods known in the art, such as by molecular weight fractionation of asolution of crystalline isotactic polypropylene having a relativelybroad molecular weight distribution, obtained by polymerization. Asuitable method of molecular weight fractionation is the fractionalprecipitation by decreasing the power of the solvent, or the temperatureraising elution fractionation on chromatographic columns (such as theDethrault method and the Baker-Williams method). However, other methodsmay be used in the present invention.

The crystallizable isotactic polypropylene segment (the Block A segment)of the block copolymer of the present invention may be produced by manyprocesses.

Preferably, it is produced by polymerizing propylene or co-polymerizingpropylene and other alpha-olefins, in the presence of a coordinationcatalyst, such as a Ziegler-Natta catalyst, a metallocene catalyst orother catalysts capable of producing an isotactic polypropylene. Thethus obtained isotactic polypropylenes may have a terminal functionalgroup, such as a double bond of an unsaturated hydrocarbon, in order tobe used in the preparation of the block copolymers of the invention.

More specifically, without limiting purposes, a crystallizable isotacticpolypropylene having a terminal double bond may be obtained by using aZiegler-Natta catalyst system, comprising a tetravalent halogenatedtitanium compound and triethyl aluminum supported on MgCl₂, or by usinga metallocene catalyst system, comprisingethylene-bis(tetreahydroindenyl)zirconiumdichloride, triethylaluminumand methylalminoxane (T. Shiono, K. Soga, Macromolecules, Vol. 25, 3356(1992);T. Hayashi, Y. Inoue, R. Chujo, Y. Doi, Polymer Vol. 30, 1714(1989)).

More preferably, a metallocene catalyst system is used, in order toobtain a crystallizable isotactic polypropylene with narrow molecularweight distribution, having a terminal double bond.

The presence of terminal double bonds on the isotactic polypropylenechains may be detected by general methods known in the state of the art.For instance, the existence of a terminal double bond can be confirmedaccording to the carbon atom assignments reported in Macromolecules,Vol. 21, page 2675 (1988), by ¹³C-NMR spectroscopy of the polymersolution.

Another terminal group of the polypropylene chain may have a1-methylbutane structure. Crystallizable isotactic polypropylenes havingthis kind of terminal double bond can be suitably used for thepreparation of the novel block copolymers of the present invention.

Another method of preparation of isotactic polypropylene is thecistactic living 1,4-polymerization of a conjugated diene monomer, suchas (E)-2-methyl-1,3-pentadiene, which is a dimer of propylene and can bepolymerized by using a so-called half-metallocene catalyst, such asmethoxycarbonyl-methylcyclopentadienyl-trichloro-titanium, followed bycatalytic hydrogenation reaction that maintains the stereoregularity,for instance by using the Lindlar catalyst or similar catalysts.

A crystallizable isotactic polypropylene can be made even by using theabove reported methods together, carrying out a stereospecificpolymerization and a living polymerization at the same time.

In these preparation methods, using the cistactic living1,4-polymerization of a conjugated diene monomer, the terminal doublebond, which is necessary for the process previously mentioned, is nolonger necessary because there is already a reactive group having aliving terminal.

While a crystallizable isotactic polypropylene can be made according tothe production methods mentioned above, the process for producing theblock copolymers of the present invention is not limited by theseexamples.

In the following, the amorphous Block B segment will be described morein details.

The Block B segment is an amorphous olefin elastomeric block segment,and more preferably the Block B segment is an olefin elastomeric blocksegment obtained by the polymerization of an olefinic unsaturatedmonomer, so that the block copolymer A-B (I) corresponds to thefollowing formula (I)′:

or the tri-block copolymer A-B-A (II) corresponds to the followingformula (II)′:

wherein A is the Block A segment; X is hydrogen, or two X groups linkedto two adjacent carbon atoms form a carbon-carbon double bond; thegroups R¹ to R⁶ are independently hydrogen or an unsaturated orsaturated alkyl group, having 1 to 8 carbon atoms; j, k and l areindependently 0 or an integer >0, and at least one of j, k and l is aninteger >0. More preferably, j, k and l, the same or different from eachother, are integers comprised between 0 and 10,000.

The block B segment, which is substantially represented in the aboveformulae (I)′ and (II)″, may contain units derived from a polymerizationinitiator or a coupling agent.

Suitable olefinic unsaturated monomers are alpha-olefins having 2 to 20carbon atoms (including those having an aromatic group in the sidechain), such as ethylene, propylene, 1-butene and styrene, anddi-olefins containing 4 to 20 carbon atoms, and preferably conjugateddi-olefin such as butadiene, isoprene, 2-methyl-1,3-pentadiene and thelike.

Non limiting examples of amorphous elastomer blocks, used as the Block Bsegment, are ethylene-propylene-copolymer elastomers,ethylene-butene-copolymer elastomers, copolymer elastomers consisting ofethylene and an olefin having 2 to 20 carbon atoms (including olefinshaving aromatic side chain group) or monomers containing 2 or more ofthese olefins, block copolymers consisting of ethylene-propylene blockcopolymers obtained by multi-stage polymerization, and copolymerscontaining one or more conjugated dienes, such as block copolymers ofethylene with butadiene, isoprene and 2-methyl-1,3-pentadiene.

It is important to the invention that the above-mentioned Block Bsegment is amorphous. In fact, the presence in such segment of manymethylene chains and many stereoregular methylethylene chains is notdesired, because they show the properties of a polyethylene crystal anda polypropylene crystal respectively. By “amorphous” is meant herein apolymer segment having very low crystallinity or totally amorphous; theBlock B segment has preferably a solubility in xylene at roomtemperature >70% by weight, preferably >80%, and even morepreferably >90% by weight.

With reference to the molecular weight of the Block B segment of thepresent invention, the length of the polymer chain must be sufficient toretain the polymer characteristics. The molecular weight is preferably≧100 g/mol, more preferably ≧1000 g/mol. Even more preferably, thepolymer chain is long enough to maintain a radius of gyration or anend-to-end distance comparable to the lamella thickness of polypropylenecrystals.

There is no limit for the maximum molecular weight, as long as thepolymer maintains an appropriate melt fluidity. More preferably, themolecular weight ranges from 100 to 500,000 g/mol.

Furthermore, with respect to the molecular weight distribution of theBlock B segment, narrow values are preferred, as already explained forthe crystallizable Block A. Preferably, Mw/Mn is ≦2.0. Livingpolymerization is suitable for the production of an olefinic elastomerhaving a narrow molecular weight distribution.

More preferably, living polymerization using an organometallic compoundas an initiator is used for the preparation of the Block B, due to thefact that the amorphous block structure of the Block B can be controlledmore precisely by sequentially changing monomers (“New polymerexperimental technology 2, Synthesis and reaction (1) Synthesis ofaddition polymers”, edited by the Society of Polymer Science, Japan,Kyoritsu Publishing, page 133 (1995)).

Among the polymerization initiators having such characteristics,bifunctional anion polymerization initiators are suitable for preparingthe tri-block copolymer of the invention. However, commonly knownprocesses may be employed in the preparation of the Block B segment,such as living cation polymerization, living coordinationpolymerization, group transfer polymerization and the like; commonlyknown catalysts and reaction systems may be used. The process forproducing the block copolymer of the present invention is not limited tothe methods mentioned above.

In the preparation of the Block B segment, every condition used for anaddition polymerization and a stereospecific polymerization, such as1,4-polymerization, 1,2-polymerization, head-to-head or head-to-tailaddition, cistactic and transtactic polymerization, can be used for thepolymerization of a conjugated diene monomer. More precisely, a monomerhaving a carbon-to-carbon double bond in the main chain or side chain ofthe Block B segment may be used.

It is also possible to produce an amorphous olefinic elastomer byhydrogenation of such carbon-to-carbon double bond, by usingmethodologies known in the state of the art. This method is preferred,since the hydrogenation of the carbon-to-carbon double bonds leads to anincrease of torsional freedom in the intramolecule, thus dramaticallyenhancing the number of rotational isomers; the consequent increase inentropy leads to an improvement of the properties of the elastomer.

Suitable examples of hydrogenation reaction catalysts are Ni-containingcatalysts or Pt-containing catalysts supported on calcium carbonate(Lindlar catalyst), and the reaction may be performed under reactionconditions well known in the art, for instance at room temperature andpressure, at high temperature and pressure, in a fluid bed system, in afixed bed system and the like, in a solvent such as water, in a polarsolvent or in a non-polar solvent.

It is preferable to work under mild reaction conditions in order tohydrogenate all the unsaturated hydrocarbons, at the same time avoidingthe decomposition of the polymer chains (JP-A-1999-349622);nevertheless, the reaction conditions of the present invention are notlimited to those mentioned above.

As already reported above, in the block copolymers of the presentinvention, the Block A segment and the Block B segment may be preparedseparately, at the same time or sequentially.

In the following are described the processes for producing the blockcopolymer of formula A-B (I).

When the A-B block copolymer is prepared by a coupling reaction using acoupling agent, after the separate preparation of the Block A segmentand the Block B segment, it is preferably added a coupling agent whichreacts either with the Block A segment or with the Block B segment, saidcoupling agent being employed in a quantity slightly higher than theequal molar quantity, and then the formation of A—A or B—B is avoided byadding the residual block segment (B segment or A segment). Thepreparation process of the present invention is not limited to theabove-mentioned example.

A preferred process for preparing a block copolymer of formula A-B (I)of the present invention is shown in the following: as mentioned above,an active terminal carbanion is obtained in a solvent, such as anon-polar solvent, by a reaction between a terminal unsaturated bond ofan isotactic polypropylene and an organometallic compound, such aslithium naphthalene, t-butyllithium, s-butyllithium and the like.

Moreover, as mentioned above, a terminal carbanion is obtained by aliving anion polymerization of an olefinic unsaturated monomer.

A block copolymer is then obtained by the coupling reaction of each ofthe terminal carbanions obtained above.

As coupling agents, hydrocarbons having both the terminal carbon atomshalogenated, or halogenated silane compounds can be mentioned withoutlimitation.

The above-mentioned coupling reaction is preferred, because it ispossible to clarify the structure of the obtained block copolymers, bysampling during the preparation stages of each block segment.

Another preferred process for producing the block copolymer of thepresent invention comprises the polymerization of an olefinicunsaturated monomer by sequential living anion polymerization, using acarbanion obtained by a reaction between a terminal unsaturated bond ofan isotactic polypropylene and an organometallic compound as aninitiating point of the polymerization; in this way, the polymercharacteristics such as the molecular weight, molecular weightdistribution, stereoregularity and the like, can be controlled byregulating the quantity of olefinic unsaturated monomer or by changingthe reaction system.

Another process for preparing a novel crystallizable block copolymeraccording to the present invention is reported below, without limitingthe scope of the present invention: the cistactic living1,4-polymerization of conjugated diene, such as(E)-2-methyl-1-3-pentadiene, which is the dimer of propylene, is carriedout by means of a half-metallocene catalyst, such asmethoxycarbonyl-methyl-cyclopentadienyl-trichloro-titanium, followed bythe addition of diene monomers, such as butadiene, isoprene and the liketo effect sequential cistactic living 1,4-polymerization; the thusobtained block copolymer is then submitted to a catalytic hydrogenationreaction, maintaining the stereoregularity by using a Lindlar catalystor the like. In this way, the polymer block segment of the propylenedimer is transformed by hydrogenation into an isotactic polypropylene,and at the same time the polymer block segment of the polymer obtainedby sequential polymerization of the diene monomer is modified byhydrogenation into an olefinic elastomer, which is a saturatedhydrocarbon.

In the following are described the processes for producing the tri-blockcopolymer of formula A-B-A (II).

A preferred process for preparing a tri-block copolymer of the presentinvention is shown below: as reported above, an active terminalcarbanion is obtained in a solvent, such as a non-polar solvent, byreaction between a terminal unsaturated bond of an isotacticpolypropylene and an organometallic compound, such as lithiumnaphthalene, t-butyllithium, s-butyllithium and the like.

Moreover, as mentioned above, a terminal carbanion is obtained by aliving anion polymerization of an olefinic unsaturated monomer.

Carbanions at both terminals are obtained by a living anionpolymerization, using a bifunctional initiator.

A tri-block copolymer is then obtained by the cross-coupling reaction ofeach of terminal carbanions obtained above.

As coupling agents, hydrocarbons having both the terminal carbon atomshalogenated, or halogenated silane compounds can be used.

The above-mentioned reactions are preferred, because it is possible toclarify the structure of the block copolymers finally obtained, bysampling during the preparation stages of each block segment.

Another preferred process for producing the tri-block copolymer of thepresent invention comprises the polymerization of an olefinicunsaturated monomer by sequential living anion polymerization, using acarbanion obtained by a reaction between a terminal unsaturated bond ofan isotactic polypropylene and an organometallic compound as aninitiating point of the polymerization, followed by a dimerizationreaction using a coupling agent; in this way, the polymercharacteristics such as the molecular weight and molecular weightdistribution can be controlled.

Another embodiment of the process of the present invention to obtain anovel crystallizable tri-block copolymer is reported in the following,without limiting the scope of the present invention: the cistacticliving 1,4-polymerization of a conjugated diene as a monomer, such as(E)-2-methyl-1-3-pentadiene, which is a dimer of propylene, is carriedout by means of a half-metallocene catalyst, such asmethoxycarbonyl-methyl-cyclopentadienyl-trichloro-titanium, followed bythe addition of diene monomers, such as butadiene, isoprene and the liketo effect sequential cistactic living 1,4-polymerization; the thusobtained block copolymer is then submitted to a catalytic hydrogenationreaction, maintaining the stereoregularity by using a Lindlar catalystor the like. In this way, the polymer block segment of the propylenedimer is transformed by hydrogenation into an isotactic polypropylene,and at the same time the polymer block segment of the polymer obtainedby sequential polymerization of the diene monomer is modified byhydrogenation into an olefinic elastomer, which is a saturatedhydrocarbon.

The scope of the present invention is not limited to these methods.

With reference to the conformation of the polymer chain of a crystallineisotactic polypropylene, which remarkably affects the mechanicalproperties of said polypropylene, whether said conformation is lead by afully extended conformation or a certain fixed chain folding isessentially a kinetic problem, related to the external environment suchas rheological environment and elongation strain, crystallizationtemperature, thermal hysteresis and the like; differently, for thecrystallizable new block copolymers of the present invention obtained asmentioned above, an equilibrium folds derived from the microstructurecan be formed and the number of such folds may be controlled by themagnitude of the unperturbed dimension of the amorphous block chain B.

In addition, since the new crystallizable block copolymer of the presentinvention is a copolymer with a controlled structure, both in thecrystallizable segments and in the dispersion of the amorphous elastomersegments, and decomposition can be suppressed, the block copolymer ofthe present invention is preferably used as a molding material as it is,or it may be used as a resin modifying agent, as a compatibilizer,surface surfactant, modifier. Moreover, it may be used as an agent toimprove the mechanical properties of the products obtained by injectionmolding of general polymers and polymer blends, of the products obtainedby blow molding or extrusion molding, such as fibers, films, sheets andfoamed articles having an homogeneous structure as a whole, excellentmoldability, a good balance in mechanical properties and recyclability,which is determined by the stabilization of the phase structure in thecase of re-heating.

In particular, the novel crystallizable block copolymers of the presentinvention show excellent mechanical properties and are endowed with highstability; moreover, they solve the problem connected to recyclingdifficulty.

The block copolymers of the present invention may be suitably used inthe automotive industry, for appliance materials and parts, or ascompatibilizers, surfactants, modifiers and agents for improving themechanical properties of polymers and polymer blends useful in themanufacture of packaging material for food, cosmetic formulations andmedical formulations. For the above purposes, the block copolymers ofthe present invention may be mixed with polyolefins, such aspolyethylene, polypropylene and the like, polyvinylchloride,polyvinylalcohol, polyacrylonitrile, polyacrylic acid plastics, dieneplastics, thermoplastics, such as polyamides, polyesters, polycarbonatesand thermoplastic elastomers.

Further, as polymer blends, a blend of two or more kinds of polymersmentioned above, or a blend of one or more kinds of other polymersmentioned above and, when necessary, additives such as plasticizers,stabilizers and colorants may be used.

Without limiting purposes, the present invention is further illustratedby the following examples.

The methods for measuring the polymer properties reported in theexamples and in the comparative examples are shown below.

Molecular weight (Mw) and molecular weight distribution (Mw/Mn): Mw andMw/Mn were measured by GPC, under the following conditions.

Preparation of the Calibration Curve:

2 mg each of three kinds of standard polystyrene samples (manufacturedby Showa Denko K.K.) were introduced into 10 mg of1,2,4-trichlorobenzene containing 0.1% wt. of 2,6-di-t-butyl-p-chresol(BHT), and were dissolved in 1 hour, in the dark, at room temperature.

Then, the elution time of a top peak was measured by GPC measurement.

The measurements were repeated and the calibration curve was prepared bylinear approximation, using 12 molecular weights (molecular weights from580 g/mol to 8,500,000 g/mol) and top peaks elution times. The thusmeasured values were those reduced to the values for polystyrene.

Measurement on Samples:

2 mg of a sample were introduced into 5 ml of 1,2,4-trichlorobenzenecontaining 0.1% wt. of BHT and dissolved, in 2 hours, at 160° C. underagitation, followed by a GPC measurement.

Other Measuring Conditions:

Apparatus: Type 150 C: manufactured by Waters

Eluent: 1,2,4-trichlorobenzene (containing 0.1% wt. of BHT)

Columns: Shodex HT-G (1 column) and Shodex HT-806M (2 columns)

Measuring temperature: 140° C.

Preparation of samples: about 2 mg of sample were dissolved into1,2,4-trichlorobenzene (containing 0.1% wt. of BHT), for 2 hours at 160°C.

Quantity of an injected sample: 0.5 ml

Elution velocity: 1.0 ml/min

Measurement of the isotactic pentad ratio (IP) and confirmation of theterminal double bond:

The measurement of IP of a crystallizable isotactic polypropylene andthe confirmation of its terminal double bond were performed under thefollowing conditions, using GSX400 (at the ¹³C-NMR frequency of 100 MHz)made by JEOL.

The IP was calculated according the method reported in Macromolecules,Vol. 6, page 925 (1973), and the presence of a terminal double bond wasconfirmed according to the carbon assignments reported inMacromolecules, Vol.21, page 2675 (1988).

Measuring mode: Proton decoupling method

Pulse width: 8.0 micro s

Pulse frequency: 3.0 micro s

Number of integration: 20,000 times

Solvent: 1,2,4-trichlorobenzene/deutrium benzene mixed solvent (weightratio=75/25)

Internal standard compound: Hexamethyldisiloxane

Concentration of sample: 300 mg in 3.0 ml solvent

Measurement temperature: 120° C.

Confirmation of Phase Stability:

The crystallization temperature measured by DSC (Differential ScanningCalorimeter) was used as an indicator.

DSC 7 by Perkin Elmer was used as the DSC; the temperature increasevelocity was 20° C./min and the temperature decrease velocity was 10°C./min.

The confirmation of phase stability was probed by measuring the enthalpyH (the heat of fusion) that is at the second temperature decreasing.

EXAMPLE 1 Block Copolymer A-B

(1) Preparation of the Olefin Polymerization Catalyst (MetalloceneCatalyst)

A double jacket reactor equipped with agitator, reflux condenser,temperature sensor and gas inlet, was used under a controlled innertemperature.

Into said reactor, 176 ml of 2.5M n-butyl lithium-hexane solvent weredropped in 40 minutes into 700 ml THF solvent containing indene (0.4mol, 4.62 g), maintained at 0° C. Then, hexamethylphosphoroustriamide(HMPA: 0.44 mol, 76 ml) was added.

After the reactor mixture was cooled to the temperature of −78° C., 100ml of a THF solution containing 1,2-dibromoethane (0.22 mol, 19 ml) weregradually added.

The violet solution formed was heated gradually up to the roomtemperature; then it was cooled again to 0° C., and under theseconditions, the solution underwent hydrolysis by the addition of asaturated solution of ammonium chloride (200 ml).

100 ml of diethyl ether were added to this mixed solution, whichseparated into two phases; it was then transferred to a separationfunnel, and after the diethyl ether layer was sufficiently rinsed byusing water, HMPA was removed by rinsing with a water solution of coppersulfate. After drying by using anhydrous magnesium phosphate, it wasobtained a mixture of a solid and an oil, then filtered.

37 g of 1,2-bis(3-indenyl)ethane were obtained from the mixture byre-precipitation with acetone-ethanol.

48.5 ml of 1.6 M n-butyl lithium-hexane solution were dropped into 150ml of THF solution containing 1,2-bis(3-indenyl)ethane, obtained asreported above (38.8 mmol, 10 g), in 40 minutes under stirring, at thetemperature of 0° C.

The thus obtained solution was added all together to a THF solution(14.7 g/150 ml) containing zirconium tetrachloride-THF complex,separately prepared in another reactor and it was stirred for 8 hours.

The mixed solution was dried to solid by means of an evaporator; afterthe addition of 100 ml of methylene chloride, it was filtered to obtaina solid.

The thus obtained yellow solid was rinsed with toluene, then rinsed withether until the filtrate became clear and the racemic complexEt(Ind)₂ZrCl₂ was obtained.

The hydrogenation process of this complex is shown below.

In a 1-L stainless steel autoclave, 163 mg of the complex Et(Ind)₂ZrCl₂were introduced and suspended in 50 ml of methylene chloride.

Then 12 mg of black Lindlar catalyst supported on calcium carbonate(Pd/CaCO₃) were added and underwent a reaction under a hydrogen pressureof 6.8 MPa, at a temperature of 70° C., for 100 min.

After the reaction, the pressure was decreased to normal pressure, thecatalyst mixture was filtered after the addition of 50 ml of methylenechloride, the obtained liquid was dried to become solid and this solidwas re-crystallized from hot toluene, thus obtaining 110 mg ofEt(H₄Ind)₂ZrCl₂.

0.4 g (0.96 mmol) of Et(H₄Ind)₂ZrCl₂ thus precipitated were sufficientlydehydrated and underwent methylation as follows: they were introducinginto a 500-ml flask, which was sufficiently dehydrated and dried, cooledwith ice at 0° C., and 1.34 ml of 1.4 M methyl lithium-ether solutionwere added and maintained under stirring for 2 hours.

The reaction mixture was filtered under dry nitrogen, and the filtratewas concentrated; after cooling at the temperature of −20° C., themethylated Et(H₄Ind)₂ZrMe₂ was recuperated by re-precipitation. Afterrinsing 3 times with 1-L each of hexane, it was finally dried to obtainabout 0.12 g of an olefin polymerization catalyst component.

(2) Preparation of the Block A Segment

Under nitrogen atmosphere, in a 100 ml-flask, the olefin polymerizationcatalyst Et(H₄Ind)₂ZrMe₂ (5 mg), prepared as reported above, and 50 mlof a toluene solution containing 10.7% wt. methylalumoxane (made byTosoh-Akzo), we contacted for 20 minutes, at room temperature.

4 ml of a toluene solution of 0.5 mol/L tri-i-butylaluminum (hereinaftercalled “TIBA”) and 20 mol of propylene were introduced into an autoclavewith an inner volume of 6.0 L and the temperature was raised to 50° C.

Then, the metallocene catalyst prepared as reported above was introducedinto the autoclave under pressure and the polymerization was carried outfor 60 minutes. The polymer obtained was purified by a standard methodand an isotactic polypropylene having a melting point of 149.1° C. wasobtained. By ¹³C-NMR spectroscopy measurement, it was confirmed that IPwas 95% and a carbon-to-carbon double bond existed at one of the twoterminals.

GPC measurement revealed that molecular weight (Mw) was 230,000 andmolecular weight distribution (Mw/Mn) was 1.8. The ΔH (the heat offusion) obtained by DSC measurement was 80 J/g.

(3) Preparation of Block B Segment

Living anion polymerization in a vacuum line:

A 300-ml flask was set to a vacuum line in which the impurities werepurged, in order to carry out a living anion polymerization; then, 3.4 gof isoprene, previously sufficiently purified, [(1) for 1 night atreflux under agitation with CaH₂, (2) then, the solution was contactedwith sodium pellets, at room temperature, and maintained under stirringfor 24 hours or longer. A small amount of oligomers was produced at thisoperation. (3) The solution was contacted with n-butyllithium at roomtemperature, and (4) was divided into small fractions after distillationusing a Schlenk tube] were introduced into this flask by way of aSchlenk tube, under vacuum, and sufficiently purified n-hexane was alsointroduced into the flask, after distillation.

The temperature of this solution was raised to room temperature and,under constant stirring, the solution was allowed to cool to 0° C. withan ice-water bath.

3.12 ml of cyclohexane-n-hexane solution containing 0.155 mmol ofsec-butyl lithium were introduced by means of a previously equippedinlet tube with a breakable seal, to effect a living anionpolymerization.

After a reaction of 30 minutes or longer, the reacted solution wassolidified by cooling with liquid nitrogen.

0.0025 mmol of 1,2-dibromoethane as a coupling agent, previouslyprepared at the inlet tube, were added all together, and the mixture wasthen heated to −70° C. by using dry-iced methanol to cause the mixtureto liquefy and react.

A portion of this reaction mixture, having a yellowish cream color, wastaken and 100 ml of methanol were injected, and the filtered product wasdried under vacuum to obtain polymer.

It was confirmed by analysis that the polymer wascistactic-poly(1,4-isoprene) polymer, having a molecular weight (Mn) of28,800 g/mol and having a molecular weight distribution (Mw/Mn) of 1.18.

(4) Preparation of the Block Copolymer A-B

A three-inlet flask equipped with reflux, inlet tube and agitator, fromwhich impurities were sufficiently purged, was connected to the vacuumline, and 0.3 g of isotactic polypropylene obtained as reported in (2)and re-precipitated from hot xylene and then sufficiently purified wereintroduced. 80 ml of purified toluene, distilled under vacuum, wereadded and, after replacement of the inner atmosphere with argon,polypropylene was totally dissolved by heating at reflux, at thetemperature of 110° C.

The temperature was decreased to 90° C., and a solution of n-hexanecontaining 0.001M sec-butyllithium was gradually added, to a totalamount of 0.165 ml; then the solution suddenly turned to anorange-luminescent color, thus indicating the formation of lithiumcarbanion at the terminal double bond of the isotactic polypropylene.

The temperature of this carbanion was maintained at 90° C. or higher,and the mixture having cream color, prepared as reported at paragraph(3), was added and allowed to react under stirring.

The temperature of the reaction mixture, thus decolorized, was broughtto room temperature and maintained under stirring overnight; then, thereaction mixture was poured into 2-L methanol, and a solid was separatedby filtration and dried. The isolated block copolymer was againdissolved in hot xylene and filtered, and purified by re-precipitationfrom hot xylene, by decreasing the liquid temperature to roomtemperature.

The following hydrogenation of this block copolymer was performed asreported in the description of the catalyst preparation mentioned above.

More specifically, 0.2 g of the block copolymer were introduced into a1-L stainless autoclave, and suspended in 100 ml of toluene. Calciumcarbonate-supported black Lindlar catalyst (Pd/CaCo₃) was added and thereaction was carried out for 80 minutes, under a hydrogen pressure of6.2 MPa, at a temperature of 90° C. At the end of the reaction, thepressure was reduced to the normal pressure and 100 ml of toluene wereadded. The obtained mixture was dried to a solid with evaporator, and ablock copolymer being hydrogenated almost 100% was obtained, byre-precipitating the solid from hot xylene.

The analysis of the purified block copolymer revealed by GPC measurementthat Mw was 260,000 and Mw/Mn was 2.0. The ΔH (the heat of fusion)measured by DSC of a mixture of 82 isotactic polypropylene prepared asreported in paragraph (2) and 10 cistactic-polyisoprene which ratio wasequal to the weight composition in the block copolymer mentioned abovewas 48 J/g; this value was far below the value of the isotacticpolypropylene only, and the degree of crystallization was decreased inthe case of simple mixing. On the other hand, the ΔH (the heat offusion) of the block copolymer measured by DSC was 80 J/g, whichdemonstrated the stabilization of the crystallizable phase.

EXAMPLE 2 Block Copolymer A-B

The operations reported in paragraphs (1) and (2) of Example 1 wererepeated, while step (3) was not performed.

By modifying the operation (4) of the Example 1 as mentioned below, theamorphous elastomeric block segment was prepared using a carbanion of anisotactic polypropylene as an initiator.

(4) Preparation of Block Copolymer A-B

A three-inlet flask equipped with reflux, inlet tube and agitator, fromwhich impurities were sufficiently purged was connected to the vacuumline; 0.3 g of the isotactic polypropylene obtained as reported inparagraph (2) of Example 1, re-precipitated from hot xylene andsufficiently purified, were introduced into said flask. 80 ml ofdehydrated and purified toluene were added, after distillation undervacuum, and after replacing the inner atmosphere with argon,polypropylene was totally dissolved by heating under reflux, at thetemperature of 110° C.

The temperature was lowered to 90° C., and a n-hexane solutioncontaining 0.001M sec-butyllithium was gradually added, to reach theamount of 0.165 ml; the solution suddenly turned to anorange-luminescent color, which confirmed the formation of a lithiumcarbanion at the terminal double bond of the isotactic polypropylene.

The temperature of the carbanion solution was maintained at 90° C. orhigher, and 10 mmol of isoprene previously introduced in the inlet tubewere added and allowed to react, under stirring.

The temperature of the reaction mixture, thus decolorized, was broughtto room temperature, and maintained under stirring overnight; then thereaction mixture was poured into 2-L methanol, and a solid was separatedby filtration and dried. The obtained block copolymer was againdissolved in hot xylene, filtered, and purified by re-crystallizationfrom hot xylene, by decreasing the liquid temperature to roomtemperature.

The analysis of the xylene-soluble portion revealed that it wascistactic-polyisoprene, having Mw of 2,300 and Mw/Mn of 1.20. Based onthe living anion polymerization characteristics, it was found that thesevalues were equal to the molecular weight and molecular weightdistribution of the amorphous B segment of the block copolymer thusformed.

The ΔH (the heat of fusion) measured by DSC of a mixture of 8 weightparts of isotactic polypropylene prepared as reported in paragraph (2)of Example 1, and 1 weight part of cistactic-polyisoprene prepared asreported in paragraph (4) of Example 2, was 63.7 J/g; this value was farbelow the value for the isotactic polypropylene only, and the degree ofcrystallization was decreased in the case of simple mixing. On the otherhand, the ΔH (the heat of fusion) of the block copolymer measured by DSCwas 80 J/g, which clearly indicated that the stabilization of thecrystallizable phase was achieved.

The ΔH (the heat of fusion) of the mixture of 9 weight parts of theblock copolymer and 1 weight part of cis-polyisoprene prepared asreported in paragraph (4) of Example 2 was 80 J/g, which clearlyindicated that the block copolymer contained a stable elastomer phase.

EXAMPLE 3 Block Copolymer A-B

As reported in Example 2, the operations described in paragraphs (1) and(2) of Example 1 were repeated, while (3) was modified as mentionedbelow. The operation reported in paragraph (4) of Example 1 wasperformed in the same manner, with the exception of the amorphouselastomer section, modified as reported in paragraph (3) of Example 3.

(3) Preparation of the Block B Segment

Living anion polymerization in a vacuum line:

A 300-ml flask was set to a vacuum line, in which the impurities werepurged in order to carry out a living anion polymerization; then 40 mmolof isoprene, previously sufficiently purified [(1) for 1 night at refluxunder agitation with CaH₂, (2) then, the solution was contacted withsodium pellets, at room temperature, and maintained under stirring for24 hours or longer. A small amount of oligomers was produced at thisoperation. (3) The solution was contacted with n-butyllithium at roomtemperature, and (4) was divided into small fractions after distillationusing a Schlenk tube], 40 mmol of butadiene and 20 mmol of2-methyl-1,3-pentadiene were introduced in this flask, by means of theSchlenk tube under vacuum, after distillation, and 10 ml of sufficientlypurified n-hexane was also introduced into the flask. The temperature ofthe solution was brought to room temperature, and under constantstirring, the solution was allowed to cool to 0° C. with an ice-waterbath.

3.12 ml of a cyclohexane-n-hexane solution, containing 0.155 mmol ofsec-butyllithium, were introduced by means of a previously equippedinlet tube with a breakable seal, to effect a living anionpolymerization.

After a reaction time of 10 hours or longer, the reaction mixture wassolidified by cooling with liquid nitrogen.

0.0025 mmol of 1,2-dibromoethane as a coupling agent, previouslyprepared at the inlet tube, was added all together, and the mixture washeated to −70° C. by using dry-ice methanol in order to liquefy themixture and to allow the reaction.

A portion of this reaction mixture, having a yellowish cream color, wasisolated and injected into 100 ml of methanol, and the filtered productwas dried under vacuum, thus obtaining the polymer.

The analysis confirmed that the polymer wascistactic-poly(1,4-isoprene-butadiene-2-methyl-1,3-butadiene), having amolecular weight (Mn) of 2,500 g/mol and a molecular weight distribution(Mw/Mn) of 1.2.

(4) Preparation of the Block Copolymer A-B

The operation described in paragraph (4) of Example 1 was performed inthe same manner, using the amorphous elastomer segment obtained inparagraph (3) of Ex. 3.

The ΔH (the heat of fusion) measured by DSC of the mixture of 8 weightparts of an isotactic polypropylene prepared in paragraph (2) of Example1 and 1 weight part of an elastomer prepared in paragraph (3) of Example3 was 60.7 J/g which was far below the value of the isotacticpolypropylene, and the degree of crystallization was decreased in thecase of the simple mixing.

However, the ΔH (the heat of fusion) measured by DSC of the blockcopolymer was 80 J/g, which demonstrated the stabilization of thecrystallizable phase.

EXAMPLE 4 Tri-Block Copolymer A-B-A

The operations described in paragraphs (1) and (2) of Example 1 wererepeated.

(3) Preparation of a Bifunctional Anion Polymerization Initiator

A 200-ml flask, equipped with side tubes and an agitator, sufficientlypurged from impurities in order to operate a living anionpolymerization, was connected to a vacuum line.

Sodium (1.0 g), previously charged in a side tube, was heated until itbecame liquid and the liquid was introduced into the flask; a sodiummirror was then prepared by heating the flask, in order to vaporize thesodium in the flask.

Then, 150 ml of a THF solution containing sufficiently purifiedalpha-styrene (3.4 g) were introduced from another side tube, and themixture showed a transparent red coloration. After the coloration, thereaction was maintained for 3 hours under agitation.

The obtained product was filtered by means of a glass filter to removethe excess of sodium, thus obtaining a THF solution (0.192 mmol/L) ofthe disodium salt of alpha-methylstyrene oligomer (tetramer), ready tobe used as bifunctional polymerization initiator.

(4) Preparation of the Block B Segment

Living anion polymerization in a vacuum line:

A 300-ml flask was set to a vacuum line in which the impurities werepurged, in order to carry out a living anion polymerization; then, 3.4 gof isoprene, previously sufficiently purified, [(1) for 1 night atreflux under agitation with CaH₂, (2) then, the solution was contactedwith sodium pellets, at room temperature, and maintained under stirringfor 24 hours or longer. A small amount of oligomers was produced at thisoperation. (3) The solution was contacted with n-butyllithium at roomtemperature, and (4) was divided into small fractions after distillationusing a Schlenk tube] and 4.11 g of 2-methyl-1,3-pentadiene wereintroduced in the flask by means of a different Schlenk tube, undervacuum after a distillation, and sufficiently purified n-hexane was alsointroduced into the flask after a distillation.

The temperature of this solution was raised to room temperature, andunder constant stirring, the solution was allowed to cool to 0° C. withan iced-water bath.

10 ml of the THF solution containing the disodium salt of alpha-methylstyrene oligomer (tetramer), as anion polymerization initiator, wereadded through a previously equipped inlet tube with a breakable seal;the transparent red color of the initiator quickly disappeared and themixture turned to a transparent yellow color. The formation of thecarbanions of the introduced monomer was confirmed by this color change,and the living anion polymerization was carried out.

After a reaction time of 12 hours or longer, the reacted solution wassolidified by cooling with a liquid nitrogen bath.

0.0040 mmol of 1,2-dibromoethane, previously prepared in the inlet tube,were added all together, then heated to −70° C. by using dry-icedmethanol, thus allowing the mixture to liquefy and react.

A portion of this reacted mixture was isolated and injected into 100 mlof methanol, and the filtered fraction was dried under vacuum to obtainthe polymer.

It was confirmed by analysis that the polymer waspoly((1-methyl-1-butenylene)-CO-(1,3-dimethyl-1-butenylene)), having amolecular weight (Mn) of 2.6·10⁴ g/mol and having a molecular weightdistribution Mw/Mn of 1.32.

(5) Preparation of Tri-Block Copolymer A-B-A

A three-inlet flask equipped with reflux, inlet tube and agitator, fromwhich impurities were sufficiently purged, was connected to the vacuumline, and 0.3 g of isotactic polypropylene obtained as reported in (2)and re-precipitated from hot xylene and then sufficiently purified wereintroduced. 80 ml of purified toluene, distilled under vacuum, wereadded and, after replacement of the inner atmosphere with argon,polypropylene was totally dissolved by heating at reflux, at thetemperature of 110° C.

The temperature was decreased to 90° C., and a solution of n-hexanecontaining 0.001M sec-butyllithium was gradually added, to a totalamount of 0.165 ml; then the solution suddenly turned to anorange-luminescent color, thus indicating the formation of lithiumcarbanion at the terminal double bond of the isotactic polypropylene.

The temperature of this carbanion was maintained at 90° C. or higher,and the mixture having cream color, prepared as reported at paragraph(3), was added and allowed to react under stirring.

The temperature of the reaction mixture, thus decolorized, was broughtto room temperature and maintained under stirring overnight; then, thereaction mixture was poured into 2-L methanol, and a solid was separatedby filtration and dried. The isolated block copolymer was againdissolved in hot xylene and filtered, and purified by re-precipitationfrom hot xylene, by decreasing the liquid temperature to roomtemperature.

The following hydrogenation of this block copolymer was performed asreported in the description of the catalyst preparation mentioned above.

More specifically, 0.2 g of the block copolymer were introduced into a1-L stainless autoclave, and suspended in 100 ml of toluene. Calciumcarbonate-supported black Lindlar catalyst (Pd/CaCo₃) was added and thereaction was carried out for 80 minutes, under a hydrogen pressure of6.2 MPa, at a temperature of 90° C. At the end of the reaction, thepressure was reduced to the normal pressure and 100 ml of toluene wereadded. The obtained mixture was dried to a solid with evaporator, and ablock copolymer being hydrogenated almost 100% was obtained, byre-precipitating the solid from hot xylene.

The analysis of the purified block copolymer revealed by GPC measurementthat Mw was 2,486,000 and Mw/Mn was 2.0. The ΔH (the heat of fusion)measured by DSC of a mixture of isotactic polypropylene prepared asreported in paragraph (2) andpoly((1-methyl-1-butenylene)-CO-(1,3-dimethyl-1-butenylene)), with acomposition of 5.6 weight % which is equal to the weight percentage inthe block copolymer mentioned above, was 38 J/g; this value was farbelow the value of the isotactic polypropylene only, and the degree ofcrystallization was decreased in the case of simple mixing. On the otherhand, the ΔH (the heat of fusion) of the block copolymer measured by DSCwas 78 J/g, which demonstrated the stabilization of the crystallizablephase.

EXAMPLE 5 Tri-Block Copolymer A-B-A

The operations (1) and (2) were repeated as reported in Example 4, whilesteps (3) and (4) were not performed.

By modifying the operation (5) of Example 4 as mentioned below, afterthe preparation of an amorphous elastomer segment, by using a carbanionof an isotactic polypropylene as an initiator, the coupling reaction fordimerization was carried out.

(5) Preparation of Tri-Block Copolymer A-B-A

A three-inlet flask equipped with reflux, inlet tube and agitator, fromwhich impurities were sufficiently purged, was connected to the vacuumline; 0.3 g of the isotactic polypropylene obtained as reported inparagraph (2) of Example 1, re-precipitated from hot xylene andsufficiently purified, were introduced into said flask. 80 ml ofdehydrated and purified toluene were added, after distillation undervacuum, and after replacing the inner atmosphere with argon,polypropylene was totally dissolved by heating under reflux, at thetemperature of 110° C.

The temperature was lowered to 90° C., and a n-hexane solutioncontaining 0.001M sec-butyllithium was gradually added, to reach theamount of 0.165 ml; the solution suddenly turned to anorange-luminescent color, which confirmed the formation of a lithiumcarbanion at the terminal double bond of the isotactic polypropylene.

The temperature of the carbanion solution was maintained at 90° C. orhigher, and 10 mmol of isoprene previously introduced in the inlet tubewere added and allowed to react, under stirring.

The reacted mixture of isoprene, showing the carbanion color(transparent yellow), was agitated for 6 hours and the temperature wasgradually brought to the room temperature. The obtained mixture wassolidified using a liquid nitrogen bath; after adding all together 10 mlof a toluene solution containing 0.0040 mmol of 1,2-dibromoethane, themixture was heated to −70° C. using dry-iced methanol, in allow themixture to liquefy and undergo the coupling reaction.

The temperature of the mixture was brought again to room temperature,and the mixture was filtered. The filtrate was poured into 2-L methanol,and a solid was separated by filtration and dried. The obtained blockcopolymer was again dissolved in hot xylene, filtered, and purified byre-precipitation from hot xylene, by decreasing the liquid temperatureto room temperature. The poly(isoprene) polymerized using an excess ofs-butyllithium was soluble in xylene, and the analysis revealed that itwas poly(isoprene) having Mw of 2,200 and Mw/Mn of 1.20; Based on theliving anion polymerization characteristics, it was found that thesevalues were equivalent to the molecular weight and molecular weightdistribution of the amorphous B segment of the block copolymer thusformed.

The ΔH (heat of fusion) measured by DSC of a mixture of 8 weight partsof isotactic polypropylene prepared as reported in paragraph (2) ofExample 1, and 1 weight part of poly(isoprene) isolated from xylene asreported in paragraph (5) of Example 5, was 53.7 J/g; this value was farbelow the value for the isotactic polypropylene only, and the degree ofcrystallization was decreased in the case of simple mixing. On the otherhand, the ΔH (heat of fusion) of the mixture of the block copolymer andthe poly(isoprene) prepared as reported in paragraph (5) of Example 5,at a ratio of 9 to 1 measured by DSC, was 80 J/g, which meant that themixture contained an elastomer phase in a stable condition.

EXAMPLE 6 Tri-Block Copolymer A-B-A

The operations (1), (2) and (3) of Example 4 were repeated, while step(4) of Example 4 was modified as mentioned below. The operation reportedin paragraph (5) of Example 4 was performed in the same manner, with theexception of the use of the amorphous elastomer segment modified asreported in paragraph (4) of Example 6.

(4) Preparation of the Block B Segment

Living anion polymerization in a vacuum line:

A 300-ml flask was set to a vacuum line, in which the impurities werepurged in order to carry out a living anion polymerization; then 40 mmolof isoprene previously purified, 40 mmol of butadiene, and 20 mmol of2-methyl-1,3-pentadiene [the purification of the diene monomer wascarried out as follows: (1) for 1 night at reflux under agitation withCaH₂, (2) then, the solution was contacted with sodium pellets, at roomtemperature, and maintained under stirring for 24 hours or longer. Asmall amount of oligomers was produced at this operation. (3) Thesolution was contacted with n-butyllithium at room temperature, and (4)was distilled using a Schlenk tube] were introduced in this flask, bymeans of the Schlenk tube under vacuum, after distillation, and 30 ml ofsufficiently purified toluene was also introduced into the flask, afterdistillation under vacuum.

The temperature of the solution was brought to room temperature, andunder constant stirring, the solution was allowed to cool to 0° C. withan ice-water bath.

When 10 ml of a THF solution of the bifunctional anion polymerizationinitiator, i.e. the sodium salt of alpha-methylstyrene oligomer(tetramer) obtained as mentioned above, were introduced from apreviously-equipped inlet tube with a breaker seal, the transparent redcolor of the initiator was quickly decolorized and the mixture turned totransparent yellow.

The formation of carbanions was confirmed by these phenomena, and theliving anion polymerization took place.

After a reaction time of 10 hours or longer, the liquid was cooled andsolidified by means of a liquid nitrogen bath. 10 ml of a toluenesolution containing 0.0040 mmol of 1,2-dibromoethane, previouslyprepared in the inlet tube, were added all together, and the mixture wasthen liquefied by heating to −70° C., using dry-iced methanol, thusallowing the reaction to take place.

The thus obtained yellowish cream colored reaction mixture was partiallysampled and injected into 100 ml of methanol. The residue of thefiltration was sufficiently rinsed and vacuum-dried to isolate thepolymer.

The analysis confirmed that the obtained polymer waspoly((1-methyl-1-butenylene)-CO-(1,3-dimethyl-1-butenylene)), having amolecular weight (Mn) of 2,600 g/mol and a molecular weight distribution(Mw/Mn) of 1.2.

(5) Preparation of the Tri-Block Copolymer A-B-A

The operation described in paragraph (5) of Example 4 was performed inthe same manner, with the exception that the amorphous elastomer segmentobtained in paragraph (4) of Example 6 was used.

The ΔH (heat of fusion) measured by DSC of the mixture of 8 weight partsof an isotactic polypropylene prepared in paragraph (2) of Example 1 and1 weight part of an elastomer prepared in paragraph (4) of Example 6 was62.4 J/g which was far below the value of the isotactic polypropylene,and the degree of crystallization was decreased in the case of thesimple mixing.

However, the ΔH (heat of fusion) measured by DSC of the block copolymerwas 80 J/g, which demonstrated that the stabilization of thecrystallizable phase was achieved.

Since the crystallizable block copolymer of the present invention is hasa controlled structure, besides being useful as it is for the moldingmaterial, it can be advantageously used as a compatibilizer, asurfactant, a modifier, a mechanical property improvement agent and thelike, in products obtained by injection molding of polymers and polymerblends, or in products obtained by blow or extrusion molding, such asfibers, films, sheets, foamed articles and the like, in order to obtainhomogeneous structure, good moldability, good balance of mechanicalproperties, stabilization of the phase structure and modification ofresins.

1. A block copolymer having formula A-B (I) or A-B-A (II), wherein A isa crystallizable isotactic polypropylene block segment (Block A segment)having a degree of polymerization ranging from 5 to 200,000 and amolecular weight distribution Mw/Mn<2.5, and B is an amorphous olefinicelastomeric block segment (Block B segment) having a molecular weightranging from 100 to 500,000 g/mol, and a molecular weight distribution(Mw/Mn)≦2.0.
 2. The block copolymer as claimed in claim 1, wherein theBlock A segment has an isotactic pentad ratio (IP), measured by ¹³C-NMR,≧85.0%, and a degree of polymerization ranging from 10 to 100,000. 3.The block copolymer as claimed in claim 1, wherein the Block B segmentis obtained by the polymerization of an olefinic unsaturated monomer,the block copolymer corresponding to formula (I)′:

or to formula (II)′:

wherein A is the Block A segment; X is hydrogen, or two X groups linkedto two adjacent carbon atoms form a carbon-carbon double bond; thegroups R¹ to R⁶ are independently hydrogen or an unsaturated orsaturated alkyl group, having 1 to 8 carbon atoms; j, k and l areindependently 0 or an integer >0, and at least one of j, k and l is aninteger >0.
 4. A process for producing a block copolymer having formulaA-B (I) or A-B-A (II), wherein A is a crystallizable isotacticpolypropylene block segment (Block A segment) having a degree ofpolymerization ranging from 5 to 200,000 and a molecular weightdistribution Mw/Mn<2.5, and B is an amorphous olefinic elastomeric blocksegment (Block B segment), which comprises the cross-coupling ofcarbanions using a coupling agent, wherein a first carbanion is obtainedby a reaction between a terminal unsaturated bond of an isotacticpolypropylene and an organic metal compound, and a second carbanion isobtained by living anion polymerization of an olefinic unsaturatedmonomer, using an initiator, or by polymerizing an olefinic unsaturatedmonomer by a sequential living anion polymerization using a carbanionobtained by a reaction between a terminal unsaturated bond of anisotactic polypropylene and an organic metal compound as the initiationpoint of the polymerization.
 5. The process as claimed in claim 4,wherein the Block A segment is an isotactic polypropylene block having aterminal unsaturated bond polymerized by using a metallocene catalyst.6. A process comprising forming an article comprising a block copolymerhaving formula A-B (I) or A-B-A (II), wherein A is a crystallizableisotactic polypropylene block segment (Block A segment) having a degreeof polymerization ranging from 5 to 200,000 and a molecular weightdistribution Mw/Mn<2.5, and B is an amorphous olefinic elastomeric blocksegment (Block B segment) having a molecular weight ranging from 100 to500,000 g/mol, and a molecular weight distribution (Mw/Mn)≦2.0.
 7. Theprocess of claim 6 wherein the article is selected from a molded articleor packaging material.
 8. The process of claim 7 wherein the packagingmaterial is food packaging material.
 9. The process of claim 7 whereinthe molded article is selected from automotive or appliance products.10. A process comprising preparing a polymer composition comprising ablock copolymer having formula A-B (I) or A-B-A (II), wherein A is acrystallizable isotactic polypropylene block segment (Block A segment)having a degree of polymerization ranging from 5 to 200,000 and amolecular weight distribution Mw/Mn<2.5, and B is an amorphous olefinicelastomeric block segment (Block B segment) having a molecular weightranging from 100 to 500,000 g/mol, and a molecular weight distribution(Mw/Mn)≦2.0.
 11. The process of claim 10 where the polymer compositionis selected from a cosmetic formulation or a medical formulation.
 12. Amolded article comprising a block copolymer having formula A-B (I) orA-B-A (II), wherein A is a crystallizable isotactic polypropylene blocksegment (Block A segment) having a degree of polymerization ranging from5 to 200,000 and a molecular weight distribution Mw/Mn<2.5, and B is anamorphous olefinic elastomeric block segment (Block B segment) having amolecular weight ranging from 100 to 500,000 g/mol, and a molecularweight distribution (Mw/Mn)≦2.0.
 13. Films, fibers, sheets or foamedarticles comprising a block copolymer having formula A-B (I) or A-B-A(II), wherein A is a crystallizable isotactic polypropylene blocksegment (Block A segment) having a degree of polymerization ranging from5 to 200,000 and a molecular weight distribution Mw/Mn<2.5, and B is anamorphous olefinic elastomeric block segment (Block B segment) having amolecular weight ranging from 100 to 500,000 g/mol, and a molecularweight distribution (Mw/Mn)≦2.0.